Stats 287 Midterm 1

The most frequently occurring value of a data set is called the a. range. b. mode. c. mean. d. median.

B

The coefficient of correlation a. is the same as the coefficient of determination. b. can be larger than 1. c. cannot be larger than 1. d. cannot be negative.

C

The difference between the largest and the smallest data values is the a. variance. b. interquartile range. c. range. d. coefficient of variation.

C

The measure of variability that is influenced most by extreme values is a. the variance. b. the standard deviation. c. the range. d. the interquartile range.

C

The measurement scale suitable for quantitative data is a. ordinal scale. b. nominal scale. c. either interval or ratio scale. d. only interval scale.

C

The variance of a sample was reported to be 144. The report indicated that = 7200. What is the sample size? a. 49 b. 50 c. 51 d. 52

C

When a percentage of the smallest and largest values are deleted from a data set, the mean of the remaining data values is the a. geometric mean. b. weighted mean. c. trimmed mean. d. interquartile mean

C

Data collected over several time periods are a. time series data. b. time controlled data. c. cross-sectional data. d. categorical data.

A

Geometric mean is a measure of a. location. b. dispersion. c. variability. d. weight.

A

If the data distribution is symmetric, the skewness is a. 0. b. .5. c. 1. d. positive.

A

A histogram is a. a graphical presentation of a frequency or relative frequency distribution. b. a graphical method of presenting a cumulative frequency or a cumulative relative frequency distribution. c. the history of data elements. d. the same as a pie chart.

A

In computing the mean of a sample, the value of ∑xi is divided by a. n. b. n - 1. c. n + 1. d. n - 2.

A

On a street, the houses are numbered from 300 to 450. The house numbers are examples of a. categorical data. b. quantitative data. c. both quantitative and categorical data. d. neither quantitative nor categorical data.

A

The entities on which data are collected are a. elements. b. populations. c. samples. d. observations.

A

When data are positively skewed, the mean will usually be a. greater than the median. b. smaller than the median. c. equal to the median. d. positive.

A

Which of the following symbols represents the variance of the population? a. σ2 b. σ c. μ d._ x

A

Which of the following is not a scale of measurement? a. Nominal b. Ordinal c. Interval d. Primal

D

46. The hourly wages of a sample of 130 system analysts are given below. mean = 60 range = 20 mode = 73 variance = 324 median = 74 The coefficient of variation equals a. 0.30%. b. 30%. c. 5.4%. d. 54%.

B

A numerical measure of linear association between two variables is the a. variance. b. covariance. c. standard deviation. d. coefficient of variation

B

The sum of deviations of the individual data elements from their mean is a. always greater than zero. b. always less than zero. c. sometimes greater than and sometimes less than zero, depending on the data elements. d. always equal to zero.

D

Which of the following symbols represents the mean of the sample? a. σ2 b. σ c. μ d. _ x

D

A characteristic of interest for the elements is called a a. sample. b. data set. c. variable. d. quality

C

The variance can never be a. zero. b. larger than the standard deviation. c. negative. d. smaller than the standard deviation.

C

The variance of a sample of 81 observations equals 64. The standard deviation of the sample equals a. 9. b. 4096. c. 8. d. 6561.

C

A researcher has collected the following sample data. The mean of the sample is 5. 3 5 12 3 2 The standard deviation is a. 8.944. b. 4.062. c. 13.2. d. 16.5.

B

Five hundred residents of a city are polled to obtain information on voting intentions in an upcoming city election. The five hundred residents in this study is an example of a(n) a. census. b. sample. c. observation. d. population.

B

In a scatter diagram, a line that provides an approximation of the relationship between the variables is known as a a. determination line. b. trend line. c. correlation axis. d. zero-bias line.

B

The coefficient of variation is a. the same as the variance. b. the standard deviation divided by the mean times 100. c. the square of the standard deviation. d. the mean divided by the standard deviation.

B

The correlation coefficient ranges between a. 0 and 1. b. -1 and +1. c. minus infinity and plus infinity. d. 1 and 100.

B

The first quartile a. contains at least one third of the data elements. b. is the same as the 25th percentile c. is the same as the 50th percentile. d. is the same as the 75th percentile.

B

The number observations in a complete data set having 10 elements and 5 variables is a. 5. b. 10. c. 25. d. 50

B

The owner of a factory regularly requests a graphical summary of all employees' salaries. The graphical summary of salaries is an example of a. a sample. b. descriptive statistics. c. statistical inference. d. an experiment.

B

The sample size a. can be larger than the population size. b. is always smaller than the population size. c. can be larger or smaller than the population size. d. is always equal to the size of the population.

B

The set of measurements collected for a particular element are called a. variables. b. observations. c. samples. d. populations.

B

The variance of a sample of 169 observations equals 576. The standard deviation of the sample equals a. 13. b. 24. c. 576. d. 28,561.

B

Which of the following is not a measure of variability? a. The range b. The 50th percentile c. The standard deviation d. The interquartile range

B

Which of the following provides a measure of central location for the data? a. Standard deviation b. Mean c. Variance d. Range

B

Which of the following symbols represents the standard deviation of the population? a. σ2 b. σ c. μ d. _ x

B

A numerical value used as a summary measure for a sample, such as sample mean, is known as a a. population parameter. b. sample parameter. c. sample statistic. d. population mean

C

All the data collected in a particular study are referred to as the a. inference b. variable. c. data set. d. population.

C

An unusually small or unusually large data value is called a. correlation coefficient. b. a deviation. c. an outlier. d. a variable.

C

Arithmetic operations provide meaningful results for variables that a. use any scale of measurement except nominal. a. use any scale of measurement except nominal. b. appear as non-numerical values. c. are quantitative. d. have non-negative values.

C

Data a. are always numeric. b. are always non-numeric. c. are the raw material of statistics. d. are always categorical.

C

Data collected at the same, or approximately the same point in time are a. time series data. b. approximate time series data. c. cross-sectional data. d. approximate data.

C

Growth factors for the population of Chattanooga in the past two years have been 8 and 12. The geometric mean has a value of a. 20. b.sqrt 20. c.sqrt 96. d. 96

C

In a five number summary, which of the following is not used for data summarization? a. The smallest value b. The largest value c. The mean d. The 25th percentile d. The 25th percentile

C

Quantitative data a. are always non-numeric. b. may be either numeric or non-numeric. c. are always numeric. d. are never numeric

C

The 75th percentile is referred to as the a. first quartile. b. second quartile. c. third quartile. d. fourth quartile.

C

The __________ can be interpreted as the number of standard deviations a data value is from the mean of all the data values. a. skewness b. coefficient of variation c. z-score d. correlation coefficient

C

The median of a sample will always equal the a. (Q1 + Q3)/2. 'b. Q4/2. c. 50th percentile. d. (smallest value + largest value)/2.

C

The median of a sample will always equal the a. (Q1 + Q3)/2. b. Q4/2. c. 50th percentile. d. (smallest value + largest value)/2.

C

The numerical value of the standard deviation can never be a. larger than the variance. b. zero. c. negative. d. smaller than the variance.

C

The sample variance a. is always smaller than the true value of the population variance. b. is always larger than the true value of the population variance. c. could be smaller, equal to, or larger than the true value of the population variance. d. can never be zero.

C

When the conclusions based upon the unaggregated data can be completely reversed if we look at the aggregated crosstabulation, the occurrence is known as a. Reverse correlation. b. Negative correlation. c. Simpson's paradox. d. Pareto's rule.

C

When the data are skewed to the right, the measure of Skewness will be a. negative. b. zero. c. positive. d. one.

C

Which of the following descriptive statistics is not measured in the same units as the data? a. 35th percentile b. Standard deviation c. Variance d. Interquartile range

C

Which of the following is a measure of variability? a. Percentiles b. Quartiles c. Interquartile range d. Geometric mean

C

Which of the following is not a measure of central location? a. Mean b. Median c. Variance d. Mode

C

Which of the following symbols represents the mean of the population? a. σ2 b. σ c. μ d. _ x

C

. A group of students had dinner at a local restaurant. The total bill for the dinner was $414.70. Each student paid his/her equal share of the bill, which was $18.85. How many student's were at the dinner? a. 4 b. 415 c. 19 d. 22

D

72. Which of the following symbols represents the size of the sample? a. σ2 b. σ c. N d. n

D

A box plot is a graphical representation of data that is based on a. the empirical rule. b. z-scores. c. a histogram. d. a five number summary.

D

A portion of the population selected to represent the population is called a. statistical inference. b. descriptive statistics. c. a census. d. a sample.

D

For data skewed to the left, the skewness is a. less than .5. b. less than 1. c. less than the mean. d. negative.

D

From a population of size 1,000, a random sample of 100 items is selected. The mean of the sample a. must be 10 times smaller than the mean of the population. b. must be equal to the mean of the population, if the sample is truly random. c. must be 10 times larger than the mean of the population. d. can be larger, smaller or equal to the mean of the population

D

From a population of size 500, a random sample of 50 items is selected. The mode of the sample a. must be 500. b. must be equal to the mode of population, if the sample is truly random. c. must be equal to the mean of the population, if the sample is truly random. d. can be larger, smaller or equal to the mode of the population

D

If two groups of numbers have the same mean, then a. their standard deviations must also be equal. b. their medians must also be equal. c. their modes must also be equal. d. other measures of location need not be the same.

D

Positive values of covariance indicate a. a positive variance of the x values. b. a positive variance of the y values. c. the standard deviation is positive. d. positive relation between the independent and the dependent variables.

D

Since a sample is a subset of the population, the sample mean a. is always smaller than the mean of the population. b. is always larger than the mean of the population. c. must be equal to the mean of the population. d. varies around the mean of the population.

D

The geometric mean of five observations is the a. same as their weighted mean. b. same as their mean. c. square root of the product of the 5 observations. d. fifth root of the product of the 5 observations

D

The interquartile range is a. the 50th percentile. b. another name for the variance. c. the difference between the largest and smallest values. d. the difference between the third quartile and the first quartile.

D

The mean of a sample a. is always equal to the mean of the population. b. is always smaller than the mean of the population. c. is computed by summing the data values and dividing the sum by (n - 1). d. is computed by summing all the data values and dividing the sum by the number of items

D

The mean of the sample a. is always smaller than the mean of the population from which the sample was taken. b. can never be zero. c. can never be negative. d. can assume any value between the highest and the lowest value in the sample

D

The measure of location which is the most likely to be influenced by extreme values in the data set is the a. range. b. median. c. mode. d. mean.

D

The numerical value of the variance a. is always larger than the numerical value of the standard deviation. b. is always smaller than the numerical value of the standard deviation. c. is negative if the mean is negative. d. can be larger or smaller than the numerical value of the standard deviation.

D

The standard deviation of a sample of 100 observations equals 64. The variance of the sample equals a. 8. b. 10. c. 6400. d. 4,096.

D

The standard deviation of a sample was reported to be 20. The report indicated that = 7200. What is the sample size? a. 16 b. 17 c. 18 d. 19

D